Objective: The purpose of this study was to determine whether chronic energy deficiency achieved with caloric restriction combined with exercise is associated with changes in the 24-hour profile of ghrelin in non-obese, pre-menopausal women.
Research methods and procedures: Twelve non-obese (BMI = 18 to 25 kg/m(2)), non-exercising women (age, 18 to 24 years) were randomly assigned to a non-exercising control group or a diet and exercise group. The 3-month diet and exercise intervention yielded a daily energy deficit of -45.7 +/- 12.4%. Serial measurements were made of body composition, energy balance, and feelings of fullness. Repeated blood sampling over 24 hours to measure ghrelin occurred before and after the study.
Results: Significant decreases in body weight, body fat, and feelings of fullness were observed in only the energy-deficit group (p < 0.05); significant changes in the following ghrelin features were found in only the deficit group (p < 0.05): elevations in baseline (+353 +/- 118 pg/mL), lunch peak (+370 +/- 102 pg/mL), dinner peak (+438 +/- 149 pg/mL), nocturnal rise (+269 +/- 77 pg/mL), and nocturnal peak (+510 +/- 143 pg/mL). In addition, we found a larger dinner decline (-197 +/- 52 pg/mL) and negative correlations between changes in the ghrelin dinner profile and changes in body weight (R = 0.784), 24-hour intake (R = 0.67), energy deficiency (R = 0.762), and feelings of fullness (R = 0.648; p < 0.05).
Discussion: Changes in ghrelin concentrations across the day after weight loss are closely associated with other physiological adaptations to energy deficiency, further supporting the role of ghrelin as a countermeasure to restore energy balance.